a) Field of the Invention
The present invention relates to a method for transfer of the refrigerant charged in a refrigerator into a refrigerant tank, provided separately from the refrigerator, without release of the refrigerant into the atmosphere and an apparatus suitable for carrying out the method as well as to a method for purging to the atmosphere non-condensible gases, having entered into the refrigerating cycle and mixed in the refrigerant gas, without release of the refrigerant into the atmosphere and an apparatus suitable for carrying out the method.
b) Prior Art Statement
Generally in the refrigerator, a charged refrigerant having a boiling point which is nearly the same as the normal temperature (for example, Fron gas CFC-11) repeatedly passes through a refrigerating cycle from evaporation, compression, condensation, pressure reduction, and then back to evaporation. When the refrigerator is disassembled totally or partially for the purpose of inspection or repair, the refrigerant is likely to be released into the atmosphere. To prevent the refrigerant from being thus dissipated to the atmosphere, the refrigerant is extracted from the refrigerating system of the refrigerator beforehand, collected into a refrigerant tank and temporarily stored therein. After completion of the inspection or repair, the refrigerant is returned from the refrigerant tank into the refrigerator.
In many of the refrigerators, non-condensible gases such as air and condensible contaminants such as water or steam having entered from outside exist together with the refrigerant gas and liquid.
Since the refrigerant liquid can be recovered relatively easily into a container such as refrigerant tank, it is extracted prior to recovery of refrigerant gas.
The refrigerant gas is liquified for recovery while the non-condensible gases and steam are separated from the refrigerant for purge to the atmosphere.
Fig. 1 is a schematic illustration of a conventional refrigerant recovery apparatus. The reference numeral 1 denotes a refrigerator. This refrigerator 1 has a refrigerating system comprising a condenser 1a, evaporator 1b and a compressor 1c. The refrigerating system has charged therein a refrigerant (for example, Fron gas CFC-11). For recovery of the refrigerant gas from the refrigerating system into a refrigerant tank 5, the refrigerant gas in the refrigerator 1 is sucked and forced by the compressor 2 and liquified as cooled by the condenser 3. Non-condensible gases such as air are mixed in the refrigerant gas and also the air contains more or less condensible contaminants such as water or steam. The refrigerant and others liquified by the condenser 3 are led into a liquid separator 4 where only the refrigerant liquid is recovered into the refrigerant tank 5 via a float valve 4a, while the non-condensible gases are purged to the atmosphere though a safety valve 4b. The gases contain the refrigerant gas having not been condensed. The reference symbol W denotes a window through which the cumulation of the liquified moisture is viewed and v a drain valve.
As having been described above, the important technical matter in the "recovery" process lies in the separation of the non-condensible gases mixed in the refrigerant gas. The separated non-condensible gases have no economical value and so they are purged to the atmosphere.
This "separation of mixed non-condensible gases" is also essential for the "purge" process which will also be described below with reference to FIG. 1.
The refrigerant under a low pressure, such as CFC-11, charged in the refrigerator 1 repeatedly goes through the aforementioned refrigerating cycle from evaporation to pressure reduction trough compression and condensation. Namely, it passes through a lower pressure than the atmospheric pressure. Therefore, air is likely to enter into the refrigerator 1 from the mechanical joints thereof so, the above-mentioned air contains condensible contaminants such as water or steam. The non-condensible gases, thus mixed into the refrigerant will cause the efficiency of the refrigerator to be lower. For maintaining or raising the refrigerator's efficiency, it is necessary to separate from the refrigerant gas the non-condensible gases, having entered into the refrigerator 1, for purge of the gases to the atmosphere. Also in this case, care must be taken for the refrigerant gas not to be purged together with the non-condensible gases to the atmosphere. To this end, a purge apparatus indicated with a solid line in Fig. 1 is utilized to return the refrigerant liquid having accumulated in the lower portion of the liquid separator 4 to the refrigerator 1 as indicated with an imaginary line with an arrow a and circulate it again through the refrigerating system, not to pass it into the refrigerant tank 5. Owing to this recirculation, the non-condensible gases are separated into the upper portion of the liquid separator 4 and released or purged through the safety valve 4b into the atmosphere.
As will be easily understandable from the above description, both the recovery and purge techniques have a common point that "only the non-condensible gases mixed in the refrigerant gas charged in the refrigerating cycle are purged to the atmosphere without losing the refrigerant gas".
In 1950's, the refrigerant was expensive and it was the economical and technical ideas to recover the refrigerant without dissipation thereof. For this purpose, it was proposed to use a conventional refrigerant recovery apparatus shown by way of example in FIG. 1. Standing on the ideas of the times, however, no efforts were made to thoroughly recover the refrigerant with higher costs than the price of the refrigerant itself.
In 1960's, various kinds of environmental pollution became an object of social concern. In 1980's, the ozone-layer destruction by Fron gas used as the refrigerant and solvent was put into dispute as a global environmental problem, and now is a time for inhibiting the dissipation of Fron into the atmosphere by recovering it thoroughly even with greater costs than the monetary value of the recovered Fron.
The prior art shown in FIG. 1 will be discussed below from the above standpoints. For recovery of the refrigerant for the purpose of inspecting the refrigerator or for a similar reason, first the refrigerant liquid is recovered and then the remaining refrigerant gas in the refrigerator is recovered. Even if the refrigerant gas in the refrigerator 1 is discharged to the full possible extent by the compressor 2, the gas pressure in the refrigerator 1 will generally fall only to 14.7 kPa. The 14.7 kPa refrigerant gas is likely to be released into the atmosphere during the disassembling and repair of the refrigerator 1. To lower the pressure of the remaining refrigerant gas in the refrigerant 1 down to about 0 to 1.33 kPa, a conventional technique using a vacuum pump 9 as shown in FIG. 2 can be used as well known to those skilled in the art. In the conventional technique shown in FIG. 2, however, the pressure of the remaining refrigerant gas in the refrigerator 1 can be lowered nearly to 0 Pa but since the delivery pressure of the vacuum pump 9 is low, the pressure of non-condensible gases in the upper space inside the liquid separator 4 will only rise up to 130 kPa. These non-condensible gases also contain a yet-to-be-condensed refrigerant gas having a partial pressure equivalent to be condensation temperature in the condenser 3. The yet-to-be-condensed refrigerant gas has a density inversely proportional to the pressure in the liquid separator 4. If the pressure is low, the partial pressure of the refrigerant gas is high as compared with that of the non-condensible gases, so that the yet-to-be-condensed refrigerant gas will have a higher density. Therefore, the high-density yet-to-be-condensed refrigerant gas will be released into the atmosphere together With the non-condensible gases purged into the atmosphere from the safety valve 4b. Such problem will take place during the recovery process as well as during the purge process.